This invention relates to a process for preparing substantially spherical particles of a cross-linked phenolic resin in a size range suitable for use as a friction particle. The resulting friction particle and friction elements containing such particles are described herein.
As used herein "friction particle" is intended to mean a particulate material having the properties of no substantial softening at elevated temperatures and a material which will not flow together or cohere with other particles, as would be the case with a "friction binder". A "friction particle" will not fuse with like friction particles, and is insoluble. A friction particle is held in place with a friction binder.
As used herein, a "friction binder" has the properties of flowability and adhesive and cohesive binding action, for the purpose of binding together the asbestos and other additives (including a friction particle) necessary for building a brake lining or other similar article of manufacture.
As used herein, "friction element" is a composition useful as linings or facings in brakes, main clutches, and banded clutch facings of power transmission speed control structures of power driven devices such as automotive vehicles. Friction elements as now made are composed in general of the filamentous reinforcing friction material, bonded with a friction binder and containing other organic or mineral friction controlling agents such as friction particles.